Device for the remote monitoring of railway switch drives

ABSTRACT

In a device for the remote monitoring of railway switch drives operated via four lines, for instance by three-phase current, or of a monitoring circuit operated via four lines and including electric contacts which are switched as a function of the position of the railway switch and via which, upon reaching of the respective end position in the switch tongue, a monitoring circuit is closed across said four lines, for a railway switch monitor fed, for instance, by direct voltage, wherein a plurality of checking planes arranged in an offset manner in the longitudinal direction of the rails are provided and in each checking plane at least four electric switching contacts are circuited together and cooperate with moved parts of the railway switch drive or railway switch, for instance a check rod, in a manner that in an end position of the switch tongue two electric switching contacts are each in the closed, and two electric switching contacts are each in the open, switching position and the switching position of each of the electric switching contacts is changed once at a changeover into the other end position of the switch tongue, the electric switching contacts of several checking planes are connected with one another in a manner that in the respective end positions of the switch tongue all of the closed electric switching contacts of said checking planes connected with one another are connected in series to form a respective monitoring circuit.

The invention relates to a device for the remote monitoring of railwayswitch drives operated via four lines, for instance by three-phasecurrent, or of a monitoring circuit operated via four lines andincluding electric contacts which are switched as a function of theposition of the railway switch and via which, upon reaching of therespective end position of the switch tongue, a monitoring circuit isclosed across said four lines, for a railway switch monitor fed, forinstance, by direct voltage, wherein a plurality of checking planesarranged in an offset manner in the longitudinal direction of the railsare provided and in each checking plane at least four electric switchingcontacts are circuited together and cooperate with moved parts of therailway switch drive or railway switch, for instance a check rod, in amanner that in an end position of the switch tongue two electricswitching contacts are each in the closed, and two electric switchingcontacts are each in the open, switching position and the switchingposition of each of the electric switching contacts is changed once at achangeover into the other end position of the switch tongue.

A device of the initially defined kind can, for instance, be taken fromEP 0 052 759 A2. In that known device, it is departed from an electronicswitch tower for feeding and remotely monitoring a railway switch drivethat is operated by three-phase current via four lines. In the starpoint connections of the motor windings are arranged contacts controlledby the drive, via which the motor windings can be connected to thethree-phase mains upon closure of the switching-on contacts and viawhich, upon rotation of the actuator and reaching of the respective newend position, a monitoring circuit is closed across the four lines andthree windings of the drive for a railway switch control circuit fed, asa rule, with direct voltage. The motor windings during rotation incorrect operation are fed symmetrically and fed asymmetrically at leastduring run-down. The monitoring device responds to the monitoringcurrents via respectively associated diodes and via connection contactsof a running-direction selector, whereby the setting current is switchedoff and the monitoring voltage is switched on with the railway switchhaving assumed one of the two end positions. Upon rotation of the driveand reaching of the respective new end position, the monitoring circuitconducted across two of the four end position contacts, the three motorwindings and the four three-phase current lines will close in a mannerthat a thus formed power circuit will signal the correct functioning ofthe electric end position switches. Further devices of the initiallydefined kind are, for instance, known from DE 36 38 681 A1, in which theremote monitoring of three-phase railway switch drives is performed bythe aid of two current-direction sensitive indicators connected inparallel via connection contacts of a running-direction selector. Amonitoring direct voltage source will feed a control potential to thetwo indicators via the three-phase line, the motor windings of the driveand the end position contacts, if the drive assumes one of its endpositions.

From DE 198 19 162 A1, another device of this type for a railway switchcomprising several switch drives can be taken. The end positions of theswitch drives are monitored in that the respective end position messagesof the individual further switch drives are combined to a summationmessage. The circuitry in this case is to safeguard that the monitoringcircuit will be realized only if all of the respective, commonlymonitored drives assume identical end positions. In the event of cut-offswitch drives, the normal positions of all of the connecting relays aremonitored.

In the initially mentioned device known from EP 0 052 759 A2, a numberof additional monitorings were effected and centrally detected. Commonto all known devices is that in the event the configuration is to beused for a plurality of checking planes without any basic changes in thelines involved, the signals combined to a summation message will incertain special cases not be suitable to monitor all of the electricswitches, and maladjustments of an electric switch may, therefore, leadto that a monitoring circuit will still build up and the respectiveerror message will not occur, or cannot be evaluated.

Departing from the initially described device for feeding and remotelymonitoring railway switch drives operated by three-phase current viafour lines, the present invention aims to ensure the safe monitoring ofseveral checking planes of one and the same railway switch without anyincrease in lines involved and without any adaptation work worthmentioning, and to enable the safe check of all electric switches of aplurality of checking planes of the same or several railway switches bya single monitoring unit. To solve this object, the device according tothe invention consists essentially in that the electric switchingcontacts of several checking planes are connected with one another in amanner that in the respective end positions of the switch tongue all ofthe closed electric switching contacts of the checking planes connectedwith one another are connected in series to form a respective monitoringcircuit. While in the known configurations only part of the electricswitches were each always connected in series and other electricswitches were connected in parallel, in the configuration of theinvention, by which the electric switching contacts of several checkingplanes are connected with one another in a manner that all of the closedelectric switching contacts, i.e. all of the connections that areconductive to form the checking circuit, are connected in series, asummation signal will actually be formed, and the monitoring circuitwill actually close, only if all of the switches of several checkingplanes are actually working and the changeover of the railway switch wascorrect.

Yet, in order to ensure correct working and the necessary check, notonly the electric switch position as such, but also the respective timerequired by the three-phase motor for the switching procedure areessential criteria to be evaluated for the correct working of therailway switch and its safety. The configuration in this respect, asknown per se, is devised such that motor windings of a three-phase motorare connected in series with the electric switching contacts andconnectable to the three-phase mains via the same, wherein theconfiguration in a particularly advantageous manner is devised such thatthe monitoring circuit corresponding to one of the end positions and themonitoring circuit corresponding to the other of the end positions areconnected with each other in a manner that the monitoring circuits willbe connected to a star point connection at the occurrence of amalfunction of at least one of the electric switching contacts or afaulty setting of the railway switch in at least one checking plane. Ifa failure of an electric switching contact occurs, a new star pointconnection can be formed with this switching arrangement, whereby thecorrect function, or a malfunction, can be directly concluded from theparameters: period of changeover and current consumption of thethree-phase drive.

An absolute potential separation between logics and power range is to beensured both in the signaling and in the setting modes of operation. Asalready mentioned in the beginning, the voltage in the monitoringcircuit, as a rule, is a direct voltage, whereas the power range, as arule, is fed by a three-phase source. During a setting procedure, it isto be taken care that the drive will be switched off upon reaching ofthe end position, in order to ensure the respective potential separationrequired for the subsequent check. If the end position is not reached,the drive will have to be switched off after a maximally admissiblerunning time, thus enabling an error to be immediately recognized orevaluated by verification of the summation signals.

The switching arrangement according to the invention, which connects aplurality of checking planes with one another, can be realized withconventional electric switches or electric switching contacts orcontrolled electric contacts such that the only expenditure involved islimited to connecting the electric contacts in the correct manner inorder to enable the desired series connection in any position. In thiscontext, the configuration advantageously is devised such that twoelectric switching contacts each of a checking plane, which havedifferent switching positions, are combined in a switch component andcooperate with a common actuating member. In principle, electricswitching contacts of a checking plane need not necessarily beredundant. However, in order to ensure the redundancy necessary for theseries connection according to the invention also in those cases, thetotal number of electric switching contacts must comply with thecriteria of redundancy.

To this end, the configuration is devised such that the number ofelectric switching contacts of all checking planes corresponds to anintegral multiple of eight. With such a number of electric switchingcontacts and the respective crosswise connection or self-monitoring modeof construction in a first checking plane, it is feasible to safelyavoid shunts or parallel connections in all switching positions suchthat the required series connection by which a summation signal can becorrectly determined for all of the electric switching contacts to bemonitored will actually always be guaranteed.

In the preferred embodiment, the device according to the invention isfurther developed in a manner that at least two electric switchingcontacts are connected in series having the same switching position atthe same end position of the switch tongue, wherein, in a furtherpreferred manner, two electric switching contacts having differentswitching positions, of an electric switch component are linked witheach other for the same end position of the switch tongue. Thissafeguards enhanced failure disclosure.

Finally, the configuration may also be devised such that three electricswitching contacts, of which at least two comprise different switchingpositions, are combined in an electric switch component to cooperatewith a common actuating member. In this case, three instead of twoelectric switching contacts are, thus, each integrated in a componentand commonly actuated, wherein two such electric switch components canbe arranged in the checking plane such that a total of six electricswitching contacts are provided.

In order to increase the operating safety, further marginal conditionare to be observed, wherein above all the wiring of the first checkingplane for the complete series connection requires special attentionirrespective of the respective position. In this context, theconfiguration may either be devised such that a separate,self-monitoring checking unit is arranged in a first one of saidchecking planes connected with one another, or be devised such that theelectric switch components allocated to a first one of said checkingplanes connected with one another are crosswisely circuited. In bothcases, it is ensured in the first checking plane that no undesiredshunts will occur and, as a result, the series connection will actuallyalways be ensured for all closed electric switching contacts of aplurality of checking planes each.

In the following, the invention will be explained in more detail by wayof exemplary embodiments of different switching states schematicallyillustrated in the drawing. Therein, FIGS. 1 to 8 depict a monitoringdevice according to the prior art, FIG. 9 illustrates the schematicstructure of the monitoring device according to the invention, and FIGS.10 to 16 are circuit diagrams of the monitoring device according to theinvention in different states of the railway switch.

FIG. 1 schematically illustrates a railway switch drive 1, which is fedvia four feed lines 2, 3, 4 and 5 and capable of being controlled andmonitored from a switch tower. The drive 1 comprises a three-phase motorincluding windings U, V and W, which are connected in a known mannerwith the electric switching contacts 6, 7, 8 and 9. A rotary currentmains including three phases L1, L2, L3 as well as the common centerpoint conductor serves as power supply means for a changeover of thedrive. Further arranged in or between two of the three externalconductors L1, L2 and L3 is a railway switch running-direction selectornot illustrated in detail, via which, for instance, the phase positionsof the currents flowing on the outer conductors L1 and L2 for theright-handed and the left-handed rotation, respectively, of the driveare interchangeable. In FIG. 1, the electric switching contacts 6, 7, 8and 9 are switched in a manner that the phases L1, L2 and L3 areinterconnected to a star point 10 such that the three-phase motor can beoperated at full power.

FIGS. 2 a and 2 b exemplify two configurations of electric switchcomponents 11 and 12, in which two electric switching contacts are eachcombined. The electric switch component 11 comprises electric switchingcontacts 6 and 7, the electric switch component 12 comprises electricswitching contacts 8 and 9. The electric switching contacts 6, 7 and 8,9 each arranged in one electric switch component 11 and 12,respectively, are allocated a common actuating member 13, which, forinstance, cooperates with grooves 15 and 16 formed in a check rod 14. InFIG. 2, the actuating member 13 of the electric switch component 12engages in the groove 15 and is therefore in the released state. Theelectric switch component 11, on the other hand, is in the tensionedposition. The switch positions illustrated in FIG. 2 correspond with oneof the two end positions of a railway switch tongue, or a movable frog.In the other end position of the switch tongue, the electric switchcomponent 12 is in the tensioned position and the electric switchcomponent 11 is in the released position. During the resetting movement,both electric switch components 11, 12 are tensioned. The two electricswitching contacts 6, 7 and 8, 9 of the electric switch components 11and 12, respectively, are in different switching positions.

From this results in the right-hand end position the circuit diagramrepresented in FIG. 3. In this right-hand end position, the feed lines2, 3, 4, 5 by the switch tower are interconnected in a manner that amonitoring circuit can build up across the four feed lines 2, 3, 4, 5and the three motor windings U, V, W.

The monitoring circuit is designed as a direct voltage circuit having afeed voltage of 60 Volts. If the correct right-hand end position of theswitch tongue is assumed, the monitoring circuit will be closed andextend across feed line 2, motor winding V, electric switching contact8, feed line 3, monitoring relay Wü, feed line 4, motor winding U,electric switching contact 7, motor winding W and feed line 5.

In FIG. 4 it is anticipated that the switch computer of the switch towerhas issued the switch command for switching the railway switch, wherebythe monitoring circuit is opened, and the feed circuit for the drivemotor is closed, by the switch tower. The winding V of the drive motorlies at the phase voltage, whereas the windings U and W lie at thephase-to-phase voltage between phases L2 and L3. The drive motor startsrotating, yet without the electric switching contacts 6, 7, 8, 9 beinginitially switched over. In this starting phase, the motor startsrunning at a torque of about 70%. Then the electric switching contacts8, 9 are switched over in the starting phase, since the actuating member13 of the electric switch component 12 is pressed out of the groove 15of the check rod. Hence results the circuitry illustrated in FIG. 1, inwhich the motor windings are star-connected.

FIG. 5 depicts the feed circuits of the drive in the run-down phaseshortly before the drive motor is switched off. In this phase, theelectric switching contacts 6, 7 too have changed their switchingpositions and thus separated the star point connection of the motorwindings. The motor is now asymmetrically excited via the phase voltageand the phase-to-phase voltage, whereby the motor continues to run at70% of the torque. Via the center point conductor Mp, the switch towerrecognizes that the changeover has been completed. At the switch tower,the feed voltage for the three-phase motor is, therefore, cut off andthe monitoring voltage for the left-hand end position is applied.Thereby, a monitoring circuit as illustrated in FIG. 6 builds up acrossfeed line 4, motor winding U, electric switching contact 6, feed line 3,monitoring relay Wü, feed line 2, motor winding V, electric switchingcontact 9, motor winding W and feed line 5.

In the illustration according to FIG. 7 the situation in which therailway switch was run through, i.e. trailed against the positiondefined by the switch command executed last, is shown. The two electricswitching contacts 6 and 7 have changed their switching positions. Dueto the contact change, the hitherto existing monitoring circuit wasinterrupted with the monitoring relay Wü being released and the drivingrelay WA being picked up. The application of the feed voltage againcauses the formation of a star connection of phases L1, L2, L3 such thatthe three-phase current can again be applied for a new changeover.

FIG. 8 illustrates a circuitry as provided according to the prior art ina monitoring device that takes into account several checking planesarranged in an offset manner in the longitudinal direction of the rails.Each of the checking planes 17, 18 and 19 comprises a checking circuitincluding two electric switch components each having two electricswitching contacts interconnected in a cascade-like manner. In theillustration according to FIG. 8, the monitoring voltage for theright-hand rail end position has been applied, and it is apparent thatthe faulty behavior of individual contact switches is not recognized.With the correct functioning of all electric switching contacts, wherebythe electric switching contact 20 would be open and the electricswitching contact 21 would be closed, the monitoring circuit shouldextend across the electric switching contact 21 as indicated by brokenlines. At a malfunctioning of the electric switching contacts 20 and 21,which are combined to an electric switch component according to theelectric switch component 11 and 12, respectively, (as illustrated inFIG. 8), the electric switching contact 20 is, however, closed and theelectric switching contact 21 is open, so that the monitoring circuitwill nevertheless be closed via the electric switching contact 20. Suchmalfunctioning will not be recognized by the switch tower, because theindividual electric switching contacts are connected in parallel, sothat no summation signal that would indicate the malfunctioning even ofa single electric switching contact will be available.

It is, therefore, proposed according to the invention that the electricswitching contacts of several checking planes are connected with oneanother in a manner that all of the closed electric switching contactsof the interconnected checking planes will be connected in series in therespective end positions of the switch tongue. A schematic illustrationof a monitoring device according to the invention is depicted in FIG. 9.The individual checking planes are denoted by 17, 18 and 19, andelectric switch components A, B, C and D are apparent, each of whichcomprises two electric switching contacts having different switchingpositions. In the following Figures, the electric switching contacts ofthe individual electric switch components are denoted by A1/2, A3/4,B1/2, B3/4, C1/2, C3/4 and D1/2, D3/4, respectively, wherein twoelectric switching contacts may each be integrated in an electric switchcomponent, for instance electric switching contacts A1/2 and A3/4 inelectric switch component A. The electric switch components can beconfigured as illustrated in FIGS. 2 a and 2 b. The drive motor isdenoted by M and the switch tower is denoted by St. FIG. 10 depicts thecircuitry of the individual electric switching contacts, wherein, basedon a first drive end position monitoring 22, three additional checkingplanes 17, 18 and 19 are consecutively arranged and connected in series.In the end position shown in FIG. 10, the monitoring circuit is closedand optically emphasized. It is apparent that all of the electricswitching contacts closed in this end position of the switch tongue areconnected in series with the monitoring circuit each extending acrossthe electric switching contacts A1/2, B1/2, C3/4 and D3/4 of theindividual checking planes. In the other end position of the switchtongue, a monitoring circuit extending across the electric switchingcontacts C1/2, D1/2, A3/4 and B3/4 of the individual checking planeswould result, as indicated by broken lines. It is apparent that themonitoring circuit connects all of the respectively closed electricswitching contacts in series such that the malfunctioning of a singleswitching contact arranged in the row will cause the interruption of themonitoring circuit in a manner that the malfunctioning of a singleelectric switching contact will be recognized any time. The monitoringcircuits corresponding to the two end positions of the switch tongue(indicated in FIG. 10 by full lines and by broken lines, respectively)are connected via connections 23 in a manner that a star connection willresult from a malfunctioning of any of the electric switching contactssuch that the three-phase motor will continue to run during thechangeover and the faulty behavior will be recognized by the switchtower on account of the exceeded changeover period. FIG. 11 depicts thesituation in which the electric switch component comprising the electricswitching contacts B1/2 and B3/4 in the checking plane 19 does notindicate the reaching of the desired end position, so that themonitoring circuit will be interrupted and a star-point connection withstar point 10 will result such that the three-phase motor will continueto run at full power. Thus, the point of connection for the star pointof the first checking plane with a conventional four-wire technique isshifted under inclusion of the individual checking planes and therebyenables the conductance of the monitoring current path through theindividual star points of the checking planes.

In the lowermost connection plane 22, a self-monitoring monitoring unitor a crosswise connection of two electric switch components may beprovided, as indicated in FIG. 10, for instance, for switch components Band D. Such a crosswise connection safeguards the constantmonitorability of all of the consecutively arranged electric switchingcontacts in the respective end position upon application of themonitoring circuit. Alternatively, a separate electric switch componentE may be employed as illustrated in FIG. 16. The electric switchcomponent E in this case may be designed in accordance with FIG. 2 b.

An external feature such as, e.g., a trailing signaling means 32 may beintegrated in this device for the remote monitoring of railway switches.

The monitoring device according to the invention can also be integratedinto a separate four-wire monitoring circuit. In FIG. 12, a contactcircuitry is illustrated, which comprises a monitoring relay 23 actingin both directions. If a single one of the numerous electric switchingcontacts fails, the monitoring current fed at, for instance, 48 Voltswill be unable to flow and the railway switch arrangement will have tobe checked. As in contrast to the illustration according to FIG. 12, inwhich the monitoring circuit is closed and consequently no error messageis indicated, the electric switch component A during the switchoveraccording to FIG. 13 will not be reset upon reaching of the desired endposition of the rail such that the monitoring relay will beshort-circuited, which will appear as an error message in the switchtower.

Overall, it is advantageous if a number of electric switching contactscorresponding to an integral multiple of eight are circuited together inthe monitoring device according to the invention, and it is, therefore,required with but two electric switch components arranged in onechecking plane to combine a group of four electric switch componentseach in a manner that a group of two electric switch components willeach be arranged in the released position and two electric switchcomponents will each be in the tensioned state, as is the case with thechecking plane 19 in FIGS. 9 to 11. A checking plane may be arranged inthe drive plane or within the extension of the tongue or of the movablefrog.

FIG. 14 depicts another structural design of an electric switchcomponent 25, 26, in which three electric switching contacts are eachcombined. Electric switch component 25 comprises electric switchingcontacts 27, 28, 29. The electric switching contacts 27, 28, 29 and 24,30, 31 respectively arranged in an electric switch component 25 and 26are allocated a common actuating member 13 cooperating, for instance,with grooves 15 and 16 formed in a check rod 14.

The electric switch component 26 engages in the groove 15 by itsactuating member 13 and is in the released position with the electricswitching contact 30 closed and the contacts 24 and 31 opened. Theelectric switch component 25 by contrast is in the tensioned state withthe electric switching contacts 27 and 28 closed and the electricswitching contacts 29 opened. The switch positions illustrated in FIG.14 correspond to one of the two end positions of the switch tongue ormovable frog.

The checking device according to the invention can be assembled byelectric switch components as described in FIG. 14. It is apparent thatall of the electric switching contacts closed in the end position of theswitch tongue are again connected in series and a monitoring circuitcloses as illustrated in FIG. 15, extending across the electricswitching contacts A11/12 and C4/3 and C13/14, respectively, of theindividual checking planes.

1. A device for remote monitoring of railway switch drives operated viafour lines, or of a monitoring circuit operated via four lines,comprising electric contacts which are switched as a function of aposition of a railway switch and via which, upon arrival in a respectiveend position of a switch tongue, a monitoring circuit is closed acrosssaid four lines for a railway switch monitor, wherein a plurality ofchecking planes (17, 18, 19) arranged in an offset manner in alongitudinal direction of rails are provided, and in each checking planeat least four electric switching contacts (A1/2, A3/4, C1/2, C3/4) arecircuited together and cooperate with moved parts of the railway switchdrive or railway switch, in a manner that in an end position of theswitch tongue two electric switching contacts (A1/2, C3/4 and C1/2,A3/4, respectively) are each in a closed switching position, and twoelectric switching contacts (C1/2, A3/4 and A1/2, C3/4, respectively)are each in an open switching position and the switching position ofeach of the electric switching contacts (A1/2, A3/4, C1/2, C3/4) ischanged once at a changeover into an other end position of the switchtongue, wherein the electric switching contacts (A1/2, A3/4, C1/2, C3/4)of several checking planes (17, 18, 19) are connected with one anotherin a manner that in the respective end positions of the switch tongueall of the closed electric switching contacts (A1/2, C3/4 and C1/2,A3/4, respectively) of said checking planes (17, 18, 19) connected withone another are connected in series to form a respective monitoringcircuit.
 2. A device according to claim 1, wherein motor windings (U, V,W) of a three-phase motor are connected in series with the electricswitching contacts (A1/2, A3/4, C1/2, C3/4) and are connectable tothree-phase mains via the contacts.
 3. A device according to claim 1,wherein a monitoring circuit corresponding to one of the end positionsof the switch tongue, and a monitoring circuit corresponding to theother of the end positions of the switch tongue are connected with eachother in a manner that the monitoring circuits will be connected to astar point connection at an occurrence of a malfunction of at least oneof the electric switching contacts or a faulty changeover of the railwayswitch in at least one checking plane.
 4. A device according to claim 1,wherein two electric switching contacts (A1/2, A3/4 or B1/2, B3/4 orC1/2, C3/4 or D1/2, D3/4, respectively) each of a checking plane (17,18, 19), which have different switching positions, are combined in anelectric switch component (A, B, C, D) and cooperate with a commonactuating member.
 5. A device according to claim 1, wherein a number ofelectric switching contacts of all checking planes (17, 18, 19)corresponds to an integral multiple of eight.
 6. A device according toclaim 1, wherein at least two electric switching contacts (A1/2, B1/2)are connected in series having the same switching position at the sameend position of the switch tongue.
 7. A device according to claim 1,wherein two electric switching contacts (A1/2, A3/4) having differentswitching positions, of an electric switch component (A) are linked witheach other for the same end position of the switch tongue.
 8. A deviceaccording to claim 1, wherein three electric switching contacts (27, 28,29), of which at least two comprise different switching positions, arecombined in an electric switch component (25) to cooperate with a commonactuating member (13).
 9. A device according to claim 1, wherein aseparate, self-monitoring checking unit is arranged in a first one ofsaid checking planes connected with one another.
 10. A device accordingto claim 1, wherein electric switch components (B1/2, B3/4, D1/2, D3/4)allocated to a first one of said checking planes connected with oneanother are crosswisely circuited.
 11. A device according to claim 2,wherein a monitoring circuit corresponding to one of the end positionsof the switch tongue, and a monitoring circuit corresponding to theother of the end positions of the switch tongue are connected with eachother in a manner that the monitoring circuits will be connected to astar point connection at an occurrence of a malfunction of at least oneof the electric switching contacts or a faulty changeover of the railwayswitch in at least one checking plane.
 12. A device according to claim2, wherein two electric switching contacts (A1/2, A3/4 or B1/2, B3/4 orC1/2, C3/4 or D1/2, D3/4, respectively) each of a checking plane (17,18, 19), which have different switching positions, are combined in anelectric switch component (A, B, C, D) and cooperate with a commonactuating member.
 13. A device according to claim 3, wherein twoelectric switching contacts (A1/2, A3/4 or B1/2, B3/4 or C1/2, C3/4 orD1/2, D3/4, respectively) each of a checking plane (17, 18, 19), whichhave different switching positions, are combined in an electric switchcomponent (A, B, C, D) and cooperate with a common actuating member. 14.A device according to claim 2, wherein a number of electric switchingcontacts of all checking planes (17, 18, 19) corresponds to an integralmultiple of eight.
 15. A device according to claim 3, wherein a numberof electric switching contacts of all checking planes (17, 18, 19)corresponds to an integral multiple of eight.
 16. A device according toclaim 4, wherein a number of electric switching contacts of all checkingplanes (17, 18, 19) corresponds to an integral multiple of eight.
 17. Adevice according to claim 2, wherein at least two electric switchingcontacts (A1/2, B1/2) are connected in series having the same switchingposition at the same end position of the switch tongue.
 18. A deviceaccording to claim 2, wherein two electric switching contacts (A1/2,A3/4) having different switching positions, of an electric switchcomponent (A) are linked with each other for the same end position ofthe switch tongue.
 19. A device according to claim 2, wherein threeelectric switching contacts (27, 28, 29), of which at least two comprisedifferent switching positions, are combined in an electric switchcomponent (25) to cooperate with a common actuating member (13).
 20. Adevice according to claim 2, wherein a separate, self-monitoringchecking unit is arranged in a first one of said checking planesconnected with one another.